The present invention relates to a reel-up in a paper machine in which paper is manufactured in a continuous web reeled onto reeling drums in the reel-up to produce paper reels, the end portions of each reeling drum being provided with a bearing housing and a braking drum with coupling device.
The reel-up commonly used comprises a stand; a driven surface winding means rotatably journalled in the stand, said web running over said surface winding means; two parallel rails mounted in the stand to support the reeling drum at its bearing housing; a secondary system movable linearly along the rails and provided in the vicinity of each rail with a linearly movable secondary body, actuators for synchronous movement of the secondary bodies, and press devices disposed on the secondary bodies to press against the bearing housings of the reeling drum in order to maintain a predetermined linear pressure in the nip between the surface winding means and the paper reel as it increases in size; and drive means for central driving of the reeling drum, said drive means comprising a rotating coupling device for coaxial connection to one of the coupling devices of the reeling drum during its rotation.
The technique described above with central driving of the reeling drum around which the paper web is wound is the result of an increasing demand for paper with uniform properties. This increasing demand applies particularly to soft paper such as tissue and similar paper for sanitary purposes for which uniform density and permeability from the innermost to the outermost layer of the reel of paper is of the utmost importance. Central driving enables variation of the linear pressure over a larger interval so that compression of the paper web in the nip between the surface winding drum and the paper reel can be reduced.
In secondary systems consisting of pivotable secondary arms with press devices in the form of rotatable rollers, the point of contact of each roller with the reeling drum generates an arc shaped path when the secondary arm is pivoted in order to adjust the reeling drum as the diameter of the paper reel increases. This changing contact point for the rollers results in uneven linear pressure during winding. Furthermore, the secondary arms can only reach a certain distance which means that the finished paper reel cannot be made larger than is permitted by the range of the arms. Drum reels-up with secondary arms are described, for instance, in the following patent specifications: EP-0 350 212, U.S. Pat. No. 3,743,199, U.S. Pat. No. 889,892, U.S. Pat. No. 3,857,524, U.S. Pat. No. 4,778,122, SE-447 816 and SE-461 976.
These problems with secondary arms are overcome by a secondary system having linearly movable secondary bodies supporting the press devices. However, as the paper reel increases in size, slipping may occur between the surface winding drum and the paper reel. Drum reels-up with linearly movable secondary bodies are described, for instance, in the following patent specifications: DE-1 225 014, U.S. Pat. No. 3,116,031 and U.S. Pat. No. 3,250,483. The last-mentioned problem is eliminated by combining the linear secondary system with said central driving. The central driving is described, for instance, in the following patent specifications: SE-9000538-0, EP-0 330 169 and U.S. Pat. No. 4,179,330.
However, it has not been possible to utilize the advantages of central driving due to difficulties in aligning and coupling together the central driving and the reeling drum during operation. A contributory cause of these difficulties is that the drive means for the central driving is arranged on a special stand at the one side of the drum reel-up and, when in inoperative position, is entirely separated from the secondary system in order to be moved linearly by its own actuator. As will be understood, the special stand with the central drive means also requires a considerable amount of space.